Theologians of the scholastic tradition, like Francisco de Vitoria (1483-1546) cemented the work of rationalization and secularization of the communication between peoples – from there the already traditional title of founder of international law. The fact that between the internal perspective of the moral and virtuous individual and the external needs of an expanding economy of exchange the moral theologians of Salamanca appeared to have been drawn to choose the latter is particularly visible in Vitoria’s De Indis, which continues to astonish the reader due to its remarkable novelty and independence of contemporary theory. Despite its avowedly Thomistic approach to many doctrinal points, the Salamanca School avoided the tension that would have arisen if Aquinas’s theory of moral virtue had been applied to its members’ thinking on economic and political matters. It seems that the School developed an economic theory and employed a type of moral theory that reflect one another. This chapter explores three avenues: Vitoria’s theology, his understanding of the dispensation of natural law, and the actual text of De Indis. Its aim is to acquire further insight into this influential text and its relationship with the doctrinal history of the discipline of international law, as well as into the moral theology of the Salamancan theologians in general. An analysis of the ideas that Vitoria poured into his influential work will also help to assess the argument that in the late Middle Ages a new world order focused on economic issues that a new economic morality adjudicated upon. Rather than in economy, the chapter seeks in a specific style of doing theology and in its partial resurgence as natural law the reasons for disorder, for that division between faith and practice and for the fragmentation between reason and moral decision.